Calculator Use
This diamond cost per carat calculator is an essential tool for jewelers, investors, and savvy shoppers. It allows you to quickly translate between the total price of a diamond and its price relative to its weight (carats). Because diamond prices are almost always quoted "per carat," understanding this calculation is the first step in comparing value between stones of different sizes and qualities.
Whether you are looking at a single stone or comparing a parcel of small diamonds (melee), this tool provides the clarity needed to ensure you are getting a fair market price.
- Total Price
- The full retail or wholesale price of the individual diamond or the total lot.
- Carat Weight
- The mass of the diamond measured in carats (1 carat = 200 milligrams). Weight is a primary driver of cost.
- Cost Per Carat
- The unit price of the diamond. This value often increases exponentially as stones cross certain weight thresholds (e.g., 0.50ct, 1.00ct).
How It Works
The diamond industry uses weight as the standard for pricing. When you use the diamond cost per carat calculator, it applies one of three basic mathematical formulas depending on the variable you need to solve for.
Cost Per Carat = Total Price ÷ Carat Weight
The "Per Carat" pricing system is unique because it isn't linear. A 2-carat diamond will almost always cost significantly more than twice the price of a 1-carat diamond of equal quality because larger rough crystals are rarer.
- Step 1: Identify the two known values (Price and Weight, or Price and Cost Per Carat).
- Step 2: Ensure the weight is accurate to at least two or three decimal places.
- Step 3: Divide or multiply according to the chosen calculation mode.
- Step 4: Compare the resulting cost per carat against industry price lists (like Rapaport) to determine value.
Calculation Example
Example: You are looking at a Round Brilliant cut diamond weighing 1.23 carats with a total price tag of $8,500. You want to know if the price per carat is competitive for its grade.
Step-by-step solution:
- Total Price = $8,500
- Total Carats = 1.23 ct
- Formula: $8,500 ÷ 1.23
- Calculate: 8500 / 1.23 = 6,910.569…
- Result: The cost per carat is $6,910.57
Common Questions
Why does the price per carat increase for larger diamonds?
This is due to the "Rarity Factor." Large, high-quality diamond rough is found much less frequently in nature than small rough. Therefore, as a diamond's weight increases, the price per carat jumps at specific "magic numbers" like 1.00ct, 1.50ct, and 2.00ct.
What is a "Magic Number" in diamond pricing?
In the diamond world, magic numbers are specific carat weights where the cost per carat increases significantly. For example, a 0.99ct diamond might cost $5,000 per carat, but a 1.00ct diamond of the same quality could jump to $7,000 per carat simply because it hit the 1-carat mark.
Is "Cost Per Carat" the same as "Total Price"?
No. The Total Price is what you pay at the register. The Cost Per Carat is the price of the diamond material itself. If you buy a 0.50ct diamond for $1,000, your total price is $1,000, but your cost per carat is $2,000.
Does the setting price affect the diamond cost per carat calculator?
Usually, when calculating cost per carat, you should only use the price of the loose stone. If you are looking at a finished ring, subtract the estimated value of the metal and labor first to get an accurate diamond-only price for the calculation.